1. Field of the Invention
The invention relates to a method for sealing an electrical coupling piece against moisture, in which electrical conductors of a line, which includes a casing of insulating material which jointly surrounds the conductors, are connected to electrical contact elements of the coupling piece, in which a ring-shaped sealing element is mounted on the casing of the line, and in which a protective body of insulating material is injection molded at the connecting point between conductors and contact elements and around the line so as to enclose the sealing element; the invention further relates to a coupling piece.
Such a method and such a coupling piece are disclosed in FP 2 485 336 A1.
2. Description of Related Art
A coupling piece in the sense of the invention may be a socket or a plug equipped with electrical sleeve contacts or with electrical plug pins. In accordance with conventional technology, such a coupling piece is mounted at the end of an electrical line for producing a so-called ready-made line which has aria chosen number of strands consisting of insulated electrical conductors which are surrounded by a common casing of insulating material. For manufacturing a coupling piece, the strands are freed from the casing over a predetermined length at the end of the line. The insulation is subsequently removed from the strands at their free ends and the exposed conductors are electrically conductively connected to the contact elements of the coupling piece. Finally, a protective body consisting of insulating material is injection molded in an injection molding tool around the connecting point between conductors and conducting elements as well as around the line. A moisture tight cover of the connecting point is achieved when the protective body is sufficiently tightly connected to the casing of the line. A corresponding connection can be achieved in conventional lines by a suitable selection of the materials of the protective body and of the casing of the line. However, in lines which are used in areas with high temperatures and in which the material of the casing is cross linked, there are problems with respect to sealing against moisture.
DE 73 40 330 U discloses a device for reducing the tension in contact points of an electrical plug which is injection molded onto an electrical line insulated with rubber. A tightly fitted plastic ring is arranged on the line, wherein the bore of the ring is smaller than the diameter of the line, at least at one location. The plastic ring is enclosed by the body of the plug.
In the method according to the above mentioned EP 2 485 336 A1, prior to injection molding the protective body, a sealing ring surrounded by two parts of a capsule is applied to the casing of the line which, in the same manner as the parts of the capsule, rest against the surface of the casing and is simultaneously injection molded onto the casing. The parts of the capsule are connected to the protective body in a moisture tight manner. This method has been found useful in practice. However, because the surface of the casing of the line is frequently not completely round, but rather is somewhat undulated, the circumferential gap between the sealing ring and the parts of the capsule, on the one hand, and the casing on the other hand, is not completely sealed off in unfavorable cases.